Corporal Ephraim W. Stone served in Co. E, 6th Tennessee Infantry. Maybe he's your man.
Please note that this is the only "Ephraim Stone" listed in the NPS Soldiers & Sailors site.
Here's a capsule history of the unit, also from the NPS Soldiers & Sailors site:
6th Infantry Regiment, organized in May, 1861, at Camp Bearegard, Jackson, Tennessee, contained men from Haywood, Madison, and Fayette counties. After fighting at Shiloh and Perryville it was placed in General Maney's and Palmer's Brigade, Army of Tennessee. In December, 1862, it was consolidated with the 9th Regiment. The unit participated in the campaigns of the army from the Murfreesborough to Atlanta, endured Hood's winter operations in Tennessee, and ended the war in North Carolina. It had about 500 men disabled at Shiloh and there were 91 killed or wounded at Perryville. The 6th/9th lost ten percent of the 412 engaged at Murfreesboro and fifty-eight percent of the 335 at Chickamauga. During December, 1863, this command totalled 335 men and 183 arms. It was included in the surrender on April 26, 1865. The field officers were Colonels George C. Porter and William H. Stephens; Lieutenant Colonels John L. Harris, William M.R. Johns, and Timothy P. Jones; and Majors James A. Wilder and Robert C. Williamson.
Hope this helps! -- Jim Huffman, Gainesville Vols